Detecting and serotyping Salmonella is essential to protecting the food supply and for understanding the epidemiology of this important food-borne pathogen. Determining the presence and serotype of the dangerous Salmonella ser. Enteritidis is of particular importance to the poultry and egg industries.
The genus Salmonella is divided into two species, S. enterica and S. bongori (33). S. enterica is further divided into seven subspecies that can be abbreviated by Roman numerals, I, II, IIIa, IIIb, IV, VI and VII. Subsp. VII was described by Multilocus Enzyme Electrophoresis (MLEE) and by phylogenetic analysis of housekeeping genes (2, 9 22). Subspecies V is now recognized as the separate species, S. bongori (28).
Serotyping further divides the Salmonellae subspecies into subtypes, or serovars (ser.), by immunologic characterization of two surface structures, O-polysaccharide (O-antigen) and flagellin protein (H-antigen) (25, 27). The current standard for Salmonella serotyping is the Kauffmann-White serotyping scheme. This method currently includes the recognized 2,587 serotypes (4, 8, 9). A serotype is represented by an antigenic formula (e.g. I 4,5,12:i:1,2) indicating the subspecies; and O, Phase 1 H, and Phase 2 H antigens. Serotypes in subspecies I are also given a name (e.g. Typhimurium).
Over 30,000 culture confirmed cases of Salmonella are identified in the United States each year. The production and quality control of the greater than 250 antisera required to generate the >2,500 serotypes using current methods is difficult and time consuming. Many isolates require three to five days or more to fully determine the serotype, which delays serotype submission to the public health data information systems. Improving the rate and accuracy of detecting and serotyping Salmonella in samples is essential to improving product safety. Thus, there is a need for compositions and methods useful to improve detection of and serotyping of Salmonella, especially within food.